The present invention relates generally to a non-stop electrical toll collection system which is one of Intelligent Transport Systems (ITS), and more particularly to a system and a method that may be advantageously applied to toll collection from a vehicle-mounted device.
Recently, a non-stop electrical toll collection system is used in which a roadside device antenna (base station antenna) installed in a toll lane on a toll road such as an express way conduct communication via a wireless link with a vehicle-mounted device (mobile station) provided on a vehicle to send toll charging information to the vehicle-mounted device at an entry or exit location. On the vehicle-mounted device that has received toll information, the toll collection is executed by taking off the toll using an electronic account settlement technique with an IC card and the like connected to the vehicle-mounted device. This system allows a vehicle to electronically pay a toll without having to stop at the tollbooth. A vehicle-mounted device for use in the Electrical Toll Collection (ETC) system, which is commercially available, is mounted for example on a dashboard in the vehicle.
The toll collection technique for use on a vehicle-mounted device in the non-stop electrical toll collection system will be described below with a conventional uniform-toll entry-location collection system in which a vehicle-mounted device is charged for a uniform-toll at an entry location of an express road as an example.
Road-to-vehicle communication between a roadside wireless device (base station) and a vehicle-mounted device functioning as a mobile station is made via control signal sent from the roadside wireless device.
As the vehicle-mounted device approaches the entry tollbooth of a toll road and enters a narrow wireless communication area of the roadside wireless device, the vehicle-mounted device receives the control signal sent from the roadside wireless device.
FIG. 5 illustrates an example of the format of data continuously sent from the roadside wireless device and the format of data sent from the vehicle-mounted device. The diagram in FIG. 5 is created in the present specification based on the description in page 41 in xe2x80x9c(Draft) Electrical Toll Collection Systemxe2x80x9d issued by Association of Radio Industries and Business, December 1999, Revision 1.2, ARIB STD-T55). FIG. 5 shows an example of the format of down-link, that is, data sent from base station (roadside wireless device) and the format of up-link, that is, data sent from mobile station (vehicle-mounted device).
Referring to FIG. 5, the data is composed of frames, each of which is made up of a plurality of slots. The first control signal, termed an xe2x80x9cNaxe2x80x9d slot, of a frame contains control information 10 on the mobile station (vehicle-mounted device). The Na slot contains a guard time, a preamble (PR) for carrier and clock synchronization, a unique word (UW1), control information and an error check code (CRC).
The Na slot, termed a frame control message slot (FCMS), is a slot for frame-multiplexing. One such frame is provided at the start of each frame only for down-link. This slot is used by the base station as a communication control slot to send Frame Control Message Channel (FCMC) composed of frame control information and TDMA slot allocation information. The control information, which will be outlined below, consists of the following fields (not shown in the FIGURE); 2-octets transmission channel control field SIG (Signaling) for layer-1 channel configuration information and so on, 1-octet frame configuration information field FSI (Frame Structure Information), 1-octet release timer information field RLT (Release Timer information), 7-octets base station service application information field SC (Service Code), and slot control information field SCI (Slot Control Identifier) for communication slot allocation. The SCI includes MDS (Message Data Slot) allocation information comprised of a 1-octet control information sub-field CI (Control Information) and a 4-octets link address field LID (Link ID).
The Nb and Nc slots are message data slots (MDS) which are slots for multiplexing data. One or more (m number of slots) such slots are allocated following the FCMS in one frame. Message data slots (MDS) are multiplexed by the base station in down-link, and by the mobile station in up-link. The number of SCIs is m for the half-duplex mode, and 2 m for the full-duplex mode. In the frame configuration for full-duplex communication, a part of message data slots (MDS) for up-link channels are commonly used for activation slots (ACTS). The attribute of a slot is determined by control information multiplexed into the FCMS.
When road-to-vehicle communication is not conducted, the roadside wireless device composing the base station, sends only Na slots. Nb and Nc slots are empty slots.
As the vehicle-mounted device composing a mobile station, enters the wireless communication area, the vehicle-mounted device first detects the unique word (UW1) 9(n) included in the Na slot of the signal sent from the roadside wireless device and makes the time slot of the vehicle-mounted device synchronize with the roadside wireless device.
Then, the vehicle-mounted device receives the control information 10(n) that follows the unique word (UW1) 9(n) and checks for a data error using the error check code (CRC) 11(n). If no error is detected as a result of error checking, the vehicle-mounted device analyzes the contents of the control information 10(n) and sends the activation channel, that is wireless link connection request signal, ACTC (Activation Channel) 15(n) to the roadside wireless device using time slots that are available for the vehicle-mounted device for transmission. An activation slot (ACTS) is used only for up-link. There are allocated six channels of windows for the activation channels used for the mobile station to register to the communication link of the base station. In the link establishment phase, the vehicle-mounted device composing a mobile station, selects one of the windows to transmit the ACTC to the base station.
In response to the ACTC 15(n) from the vehicle-mounted device, the roadside wireless device notifies the reception time slots of the vehicle-mounted device using the control information 10(n+1) in the (N+1) a slot (not shown) and sends data to the vehicle-mounted device using the (N+1) b slot or the (N+1) c slot.
The control information 10(n+1) includes information on:
type of roadside wireless device,
link address field LID (Link ID) information on vehicle-mounted device and the like
When the vehicle-mounted device has successfully received data arranged in the (N+1) b slot or (N+1) c slot, it analyzes the contents of data and sends back response data using the transmission time slot indicated by the frame control message slot (FCMS) sent from the roadside wireless device.
The data 14(n) in the Nb slot or the Nc slot includes detailed information regarding the toll collection, being transferred between the roadside wireless device and the vehicle-mounted device. The toll collection is performed normally by transferring this data.
The conventional toll charging processing system described above operates normally when the roadside wireless device is provided at a limited location, that is, at a tollbooth at the entry of a toll road and the like.
However, if this system is applied to a general public road and to a toll collection system that charges a vehicle entering a toll collection area for a toll, the problem is that an erroneous charging to the vehicle may occur.
That is, in a public road of two-way traffics, especially in a lane having a narrow width and a face to face traffic, unlike a one way tollbooth lane at an entry of a toll road, a vehicle exiting a toll collection area must also pass through the wireless communication area of the roadside wireless device.
As a result, the vehicle-mounted device executes road-to-vehicle communication with the roadside wireless device and is charged for the toll even when exiting the toll collection area. Thus, an erroneous charging occurs unless some toll collection protection is devised.
Japanese Patent Kokai Publication JP-A-8-69598 proposes a toll collection system that controls toll collection according to the direction in which a vehicle travels. This system charges a vehicle that traveling in the forward direction lane but does not charge a vehicle traveling in the opposite lane. A first antenna and a second antenna are provided near a tollbooth along the lanes to allow the tollbooth to communicate with vehicle-mounted devices for collecting tolls in non-contact mode. The first antenna and the second antenna each send information including a unique antenna number. The vehicle-mounted device receives the signals from the first antenna and the second antenna and checks the antenna numbers to determine which communication area the vehicle-mounted device has entered first. When traveling in the opposite lane, the backward-traveling flag is turned on to disable toll collection. The vehicle-mounted device uses a timer to measure the time during which the backward-traveling flag remains on and when a predetermined time has passed or the vehicle enters the communication area of a tollbooth antenna emitting different location information, clears the backward-traveling flag to enable communication. In this toll collection system, the vehicle-mounted device judges the moving direction based on information sent from the antenna and when the backward-traveling flag is on, does not collect the toll. However, the system with this configuration gives a vehicle-mounted device user a chance to evade tolls by altering the backward-direction traveling flag, for example, by turning it on.
Accordingly, it is an object of the present invention to provide a method and a system, for use in a toll collection system that charges uniform toll at a tollbooth in a toll road, that can correctly perform toll charging, via road-to-vehicle communication, only to vehicles traveling in the direction for which toll must be charged, without having to stop a vehicle.
As will become apparent from the description below, the present invention may be applied not only to a toll collection system but also to various systems in a base station that manages mobile stations.
The above and other objects of the invention are satisfied, at least in part, by providing a system including a plurality of base stations which are coupled for communication each other, in which on base station of the base stations obtains unique information on a mobile station that has entered a wireless communication range of the one base station via wireless communication with the mobile station; and notifies the unique information on the mobile station, obtained by the one of base stations, to other base station located downstream to the one base station along a moving direction of the mobile station, and in which the other base station obtains unique information on the mobile station via wireless communication with the mobile station that has entered a wireless communication range of the other base station; determines if a moving direction of the mobile station is a predetermined forward direction or a backward direction by comparing the unique information on the mobile station obtained by the other base station with the unique information notified by the one base station; and controls an execution of predetermined processing for the mobile station based on a determination result of the moving direction of the mobile station.
The system in accordance with another aspect of the present invention has a plurality of roadside wireless devices. One roadside wireless device communicating with a vehicle-mounted device on a vehicle via wireless communication notifies unique information, obtained from the vehicle-mounted device via road-to-vehicle communication, to other roadside wireless device located downstream to the one roadside wireless device, along a moving direction of the vehicle. The other roadside wireless device determines if a moving direction of the vehicle is an entry into or exit from the toll area by comparing unique information obtained from the vehicle-mounted device via road-to-vehicle communication with the unique information notified by the one roadside wireless device and based on a result of the determination, controls an execution of toll charging processing.
A method for managing a mobile station in accordance with a further aspect of the present invention uses a plurality of base stations coupled for communicating each other and comprises the steps of:
obtaining, by one base station, unique information on a mobile station that has entered a wireless communication range of said one base station, via wireless communication with the mobile station;
notifying, by one base station, the unique information on the mobile station obtained by said one base station, to other base station located downstream to said one base station along a moving direction of the mobile station;
obtaining, by said other base station, unique information on the mobile station via wireless communication with the mobile station that has entered a wireless communication range of said other base station;
determining, by said other base station, if a moving direction of the mobile station is a predetermined forward direction or a backward direction by comparing the unique information on the mobile station obtained by said other base station with the unique information notified by said one of base stations; and
controlling, by said other base station, an execution of predetermined processing for the mobile station based on a determination result of the moving direction of the mobile station.
Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description in conjunction with the accompanying drawings wherein only the preferred embodiments of the invention are shown and described, simply by way of illustration of the best mode contemplated of carrying out this invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawing and description are to be regarded as illustrative in nature, and not as restrictive.